Embodiments of the present invention relate to an apparatus and method for generating audio subband values, an apparatus and a method for generating time-domain audio samples and systems comprising any of the aforementioned apparatuses, which can for instance be implemented in the field of modern audio encoding, audio decoding or other audio transmission-related applications.
Modern digital audio processing is typically based on coding schemes which enable a significant reduction in terms of bit rates, transmission bandwidths and storage space compared to a direct transmission or storage of the respective audio data. This is achieved by encoding the audio data on the sender side and decoding the encoded data on the receiver side before, for instance, providing the decoded audio data to a listener or to a further signal processing.
Such digital audio processing systems can be implemented with respect to a wide range of parameters, typically influencing the quality of the transmitted or otherwise processed audio data, on the one hand, and computational efficiency, bandwidths and other performance-related parameters, on the other hand. Very often, higher qualities necessitate higher bit rates, an increased computational complexity and a higher storage requirement for the corresponding encoded audio data. Hence, depending on the application in mind, factors as allowable bit rates, an acceptable computational complexity and acceptable amounts of data have to be balanced with a desirable and achievable quality.
A further parameter, which is especially important in real-time applications such as a bi-directional or a mono-directional communication, the delay imposed by the different coding schemes may also play an important role. As a consequence, the delay imposed by the audio encoding and decoding poses a further constraint in terms of the previously mentioned parameters when balancing the needs and the costs of different coding schemes having a specific field of application in mind. As such digital audio systems can be applied in may different fields of applications ranging form ultra-low quality transmission to a high-end-transmission, different parameters and different constraints are very often imposed on the respective audio systems. In some applications, a lower delay may for instance necessitate a higher bit rate and, hence, an increased transmission bandwidth compared to an audio system with a higher delay, as comparable quality level.
However, in many cases, compromises may have to be taken in terms of different parameters such as bit rate, computational complexity, memory requirements, quality and delay.